Need help with dock lights for fishing

I bought a few 400 watt metal halide green bulbs for night fishing. Problem is, I put them in "arena" fixtures and the light seems to go everywhere except the water. Can I get a spot type fixture that fits these bulbs? Or do I just have to start over, and if that is the case what fixtures and bulbs do you recommend in 400 or 1000 watts.



Thanks for your help!